What To Know and Do About Knee Pain When Bending

Medically reviewed by Raynetta Samuels PT, DPT, CLT

The knee is a complex joint. It's also the strongest joint in your body, with the ability to hold up to five times your body weight. Bones, cartilage, ligaments, muscles, tendons, and fluid work together to make your knees move smoothly. An issue with any of these elements can cause pain in your knee when you bend it.

Knee pain when bending your leg is a common symptom with many possible causes. In some people, the pain stems from an injury or trauma to the knee. It might also be caused by a medical condition that causes inflammation or fluid buildup in the knee. An accurate diagnosis of your knee pain is essential for effective treatment.

How Knee Pain Presents

In general, healthcare providers classify knee pain as either acute or chronic:

• Acute pain usually occurs suddenly and lasts less than six weeks.

• Subacute pain lasts 6-12 weeks.

• Chronic knee pain lasts longer than 12 weeks.

Chronic pain can begin as acute pain, or it can develop gradually over time. About 25% of adults experience chronic knee pain.

Pain may occur in one or more locations in and around the knee, such as:

• Just above your knee

• On the front of your knee, or kneecap

• Behind your knee

• Just below your knee

• Inside or outside your knee joint

Symptoms of knee pain may be constant, or they may come and go. Specific symptoms may include:

• Sharp or stabbing pain

• Difficulty extending or bending your knee

• Swelling around your knee

• Stiffness or tightness around your knee

• Locking up of your knee

• Grinding, grating, or creaking in your knee joint

• Feeling that your knee is weak or unstable

• Warmth around parts of your knee, such as your kneecap

Depending on its cause, knee pain may worsen during periods of inactivity (such as when sitting for a long time) or periods of activity (such as when exercising).

Potential Causes of Knee Pain When Bending

A wide variety of possible causes can lead to knee pain. Certain risk factors can also increase your risk of developing knee pain, including:

• Excess body fat tissue

• A history of knee injuries

• Performing a job or sport that puts excess or repetitive stress on your knees

Having one or more of these risk factors does not necessarily mean you will develop knee pain. However, it might mean you're more likely than someone without any risk factors to experience it.

Key Terms

Ligament: Connective tissue that connects bones at joints like elbows and wrists
Tendon: A thick, flexible band of tissue that connects muscles to bones

Bursa: A small, fluid-filled sac that provides cushioning for bones, muscles, ligaments, and tendons near a joint

Acute Injury

Knee pain often results from an injury to a part of your knee. Pain may begin right after the injury, or it may be delayed. The sooner it begins, the more serious the injury may be.

These knee injuries are common in athletes and knee include:

• Torn ligament: This type of knee injury usually results from sudden twisting of your knee. It may cause bleeding, swelling, and instability in the joint. One example is an anterior cruciate ligament (ACL) tear. Your ACL connects your thigh bone (femur) and shin bone (tibia).

• Torn cartilage: This type of injury causes pain on the inside or outside of your knee joint. For example, the meniscus is a c-shaped cartilage padding in your knee that helps absorb shocks (e.g, when you run or jump). A torn meniscus often occurs due to forceful twisting or rotating of your knee—for example, stopping and starting, changing direction quickly, or lifting heavy weights.

• Ligament strain or sprain: These minor injuries are usually caused by twisting your knee. Pain from a strain or sprain is more likely to have a delayed onset, meaning you'll feel pain sometime after the injury occurs.

• Patellar fracture: A patellar fracture might include one or multiple breaks in your patella (kneecap), which may or may not separate the broken pieces of bones. It's typically caused by falling on your knee or a severe blow to your knee.

• Patellar dislocation: A dislocation is when your patella slides out of place. It often occurs due to sudden twisting or a severe blow to your knee.

Overuse Injury

Overuse is another common cause of knee pain. Using your knee too much or repeatedly in a specific motion can lead to inflammation and pain. Specific knee problems resulting from overuse include:

• Bursitis: This condition is inflammation of the bursa, which are fluid-filled sacs located between bones and nearby soft tissue, bones and tendons, and muscles. It might be caused by excessive kneeling or a direct blow to the front of your knee.

• Tendinitis: This is a soft tissue injury caused by the inflammation and swelling of a tendon. One type of tendinitis is patellar tendinitis, or jumper's knee. The patellar tendon that runs from your quadriceps (front of thigh) to your shinbone weakens. You'd feel the pain during high-impact activities like jumping.
  

• Patellofemoral pain syndrome (PFP): Also known as patellofemoral syndrome and runner's knee, PFP causes pain in the front of your knee. It often develops in people who run or jog frequently and is one of the most common causes of knee pain.

• Iliotibial band syndrome (ITBS): ITBS is inflammation of a tendon called the iliotibial (IT) band due to continual rubbing against your knee or hip bones. It's the most common cause of lateral (side) knee pain in people who run, cycle, or engage in physical activities like tennis and weight lifting.
  

Arthritis

Arthritis refers to inflammation of a joint or set of joints. Several types of arthritis can lead to knee pain when bending, including osteoarthritis (OA) and rheumatoid arthritis (RA), an autoimmune disease that attacks joints.

Osteoarthritis is a common type of arthritis that causes a gradual breakdown of joint tissues. It's the most common condition that causes knee pain. Pain from osteoarthritis might occur in a specific location or move around.

Risk factors for developing osteoarthritis include:

• Older age

• Being assigned female at birth

• Being overweight or obese (having excess fat cells)

• Previous knee injuries

• Overuse of your knee that places repetitive stress on the joint

• Genetics (family history of arthritis)

• Bone deformities

• Certain metabolic conditions, such as diabetes

Baker Cyst

Like a hinge on a door, your knee needs lubricant to allow the joint to slide back and forth. This lubricant is called synovial fluid. When your knee becomes inflamed due to injury or disease, synovial fluid might build up behind your knee.

This buildup may form a Baker cyst, a fluid-filled sac that can cause stiffness, discomfort, or pain behind the knee. It's especially painful if the cyst bursts.

Infection

Two main types of infection can affect your knee and lead to knee pain: osteomyelitis (a bone infection) and septic arthritis (a joint infection). Knee infections are usually caused by bacteria that enter body tissue through your skin or move into your knee from another part of the body.

Risk factors that can increase your risk of developing a knee infection include:

• Chronic conditions like diabetes
  

• Artificial joint implants

• Recent joint injury or surgery

• Injectable substance use disorder

• Weakened immune system (for example, due to a condition or medication)

• Hemodialysis (a medical procedure that uses an artificial kidney to filter your blood if your kidneys aren't working effectively or at all)

Possible symptoms of a knee infection include:

• Severe knee pain

• Swelling, redness, and warmth at the knee

• Inability to move the knee

• Open wound near the knee

• Fever, sweating, or chills

A knee infection is a medical emergency. If you have any of the symptoms listed above, contact your healthcare provider immediately.

When To See a Healthcare Provider

With at-home care, knee pain usually resolves within six weeks or so. However, certain symptoms suggest a more serious condition and require medical attention. Contact your healthcare provider if you have any of the following symptoms:

• Severe pain or pain that lasts longer than a few days

• Inability to put any weight on your knee

• Knee buckling or locking up

• Deformed appearance of the knee

• Inability to flex or straighten your knee

• A fever along with redness or warmth around your knee

• Extreme swelling around your knee

• Pain, swelling, tingling, numbness, or discoloration in your calf

Diagnosis

After asking about your symptoms and health history, your healthcare provider will perform a physical exam. They will assess your knees, hips, and legs as well as your overall joint health.

The provider may perform tests to diagnose the cause of your knee pain. These tests may include:

• Imaging tests: Examples include X-ray, computed tomography (CT) scan, magnetic resonance imaging (MRI) scan, ultrasound, or bone scan

• Joint fluid culture: Taking a sample of the synovial fluid from your knee and examining it under a microscope

• Blood tests: To look for evidence of infection or a systemic (whole-body) health condition

Knee Pain Treatment

Knee pain treatment depends on the cause of pain. However, treating knee pain as soon as it occurs may help it resolve more quickly.

You can treat most cases of minor knee pain on your own at home with strategies like the following:

• Rest: Avoid putting weight on your knee until the pain resolves. A cane or crutches may be helpful.

• Use cold therapy: Try applying ice packs for the first few days to reduce inflammation. Apply the ice for 15 minutes every hour, at least four times daily.

• Wrap the knee: Wear a brace or wrap your knee in an elastic bandage to keep it stable.

• Elevate the knee: Keeping the knee above your heart, if possible, will help reduce swelling.

• Take pain medications: Try over-the-counter (OTC) acetaminophen (Tylenol) or non-steroidal anti-inflammatory drugs (NSAIDs) like Advil, Aleve, or Motrin to relieve pain. Your doctor may prescribe stronger pain-relieving drugs if your pain is severe or persistent.

• Try alternative therapies: Methods such as acupuncture or magnetic pulse therapy are not scientifically proven, but some people may find some pain relief. Magnetic pulse therapy uses magnets to stimulate nerve cells.

Medical treatments for knee pain may include:

• Physical therapy: A physical therapist can work with you to develop an exercise plan that reduces pain and increases strength and flexibility in your knee.

• Corticosteroid injection: Getting a steroid shot in your knee is a short-term solution to reduce swelling and pain.

• Fluid removal: Your healthcare provider may use a needle to remove built-up fluid in your knee.

• Antibiotics: Your healthcare provider may prescribe an antibiotic drug to treat infection.

• Surgery: In severe cases, surgery might need to remove a Baker cyst, repair damage to a tendon or ligament, or replace your knee.

A Quick Review

Knee pain when bending can stem from various causes of inflammation, including injuries and underlying health conditions. Most cases of knee pain are not serious and resolve within six weeks or so with at-home care. You may be able to prevent future knee pain with strategies like wearing supportive or orthotic shoes and adjusting your exercise routine to reduce impact on your knees.

Some causes of knee pain are more severe or long-lasting and require medical treatment. Reach out to a healthcare provider if you have severe or disabling knee pain, especially if it occurs with other symptoms like a fever.

For more Health.com news, make sure to sign up for our newsletter!

Read the original article on Health.com.